Success in treating breast cancer with Herceptin (non-patent document 1) and malignant B lymphoma with Rituxan (non-patent document 2) has shown that antibodies can be used as therapeutic drugs in treatment of cancers. Some kinds of antibodies form a complex with an antigen molecule existing cell membrane, triggering an ADCC activity (non-patent document 3) and a CDC activity (non-patent document 4) so as to kill the cell expressing antigen. The antigen-antibody complex formation may trigger apoptosis. A lethal action on cells by an antibody is a peculiar function found in cells regardless of whether they are cancer cells or normal cells. Success or failure of development of antibody therapeutic drugs for treating cancers depends upon the discovery of an antigen (a cancer antigen) as a target of an antibody capable of killing all the subjected cancer cells while minimizing the effect (adverse effect) to normal cells.
Because an entire base sequence of human genome has been determined, a primary sequence of amino acid of all proteins coded on the genome can be estimated. Abnormal expression of genes that are not used for normal cells causes canceration. If the gene product thereof is a membrane protein, it becomes a target of an antibody as shown in an example of HER2/Herceptin. Based on this idea, researches for analyzing the qualitative and quantitative difference of transcriptional products between cancer cells and normal cells by using DNA microarray have been carried out in many laboratories all over the world.                [Patent document 1] Translation Publication No. Saihyou 01/062907        [Patent document 2] Translation Publication No. Saihyou 01/096401        [Non-patent document 1] Mass R, et al.: The Concordance Between the Clinical Trials Assay (CTA) and Fluorescence in Situ Hybridization (FISH) in the Herceptin Pivotal Trials.: Proc Am Soci Clin Oncol 19, 75a, 2000        [Non-patent document 2] Berinstein N L, Grillo-López A J, White C A, Bence-Bruckler I, Maloney D, Czuczman M, et al. Association of serum Rituximab (IDEC-C2B8) concentration and anti-tumor response in the treatment of recurrent low-grade or follicular non-Hodgkin's lymphoma. Annals of Oncology 1998, 9:995-1001.        [Non-patent document 3] Bruggemann M., Williams G. T., Bindon C. I., Clark M. R., Walker M. R., Jefferis R., Waldmann H., Neuberger M. S. (1987). Comparison of the effector functions of human immunoglobulin using a matched set of chimeric antibodies. J. Exp. Med., 166, 1351-1361.        [Non-patent document 4] Loos M. (1982). The classical complement pathway: mechanism of activation of the first component by antigen-antibody complexes. Prog. Allergy, 30, 135-192. Mol. Immunol. 1982 May; 19(5):651-7.        